This application requests support for a Symposium entitled "Receptors for Abused Drugs: Development and Plasticity", to be part of the program at the Annual Meeting of the Neurobehavioral Teratology Society (NBTS). The meeting will take place at the Keystone Resort in Keystone, Colorado, from July 1 to July 4, 1999. The purpose of the proposed Symposium is to present the current state of knowledge concerning the normal ontogeny of receptors for several important drugs of abuse and how these receptors are altered by acute or chronic drug exposure during development. When ingested by pregnant women, abused drugs may adversely affect fetal neurobehavioral development by several mechanisms, including direct interaction with molecular targets (i.e., receptors) in the fetal brain. Thus, it is critically important for investigators studying prenatal drug effects in humans or in animal models to understand the normal localization and time course of receptor expression during development, as well as alterations in receptor expression (and their functional consequences) that occur following developmental drug exposure. The proposed Symposium will bring together five leading researchers, each of whom will cover one of receptor classes chosen for discussion. The speakers and their topics will be Dr. Theodore Slotkin, Duke University, who will discuss nicotine receptors, Dr. Frances Leslie, University of California at Irvine, who will discuss opiate receptors, Dr. Eva Mezey, National Institute on Neurological Diseases and Stroke, who will discuss cannabinoid receptors, Dr. Ratna Sircar, Albert Einstein College of Medicine, who will discuss phencyclidine (PCP) receptors, and Dr. Jerrold Meyer, University of Massachusetts, who will discuss monoamine transporters (the "receptors" for cocaine and amphetamine). Each speaker will discuss 1) the structure, function, and localization of his/her receptor(s), 2) normal receptor ontogeny (pre- and/or postnatal), and 3) receptor plasticity during development and the functional (i.e., behavioral or physiological) consequences of such plasticity. Alcohol will not be included in this Symposium, partly because there was a recent alcohol Symposium at NBTS and also because of the wide diversity of ion channels and other moieties thought to serve as the molecular targets of alcohol action in the brain. For the purpose of wider dissemination of the Symposium presentations, a summary of the proceedings jointly authored by all of the speakers will be published in Neurotoxicology and Teratology.